Satellite radar interferometry for assessing coseismic liquefaction in Portoviejo city, induced by the Mw 7.8 2016 Pedernales, Ecuador earthquake

Abstract

The Portoviejo city, located in the central part of the Ecuadorian Pacific Coast (province of Manabi), was severely affected during the Pedernales Mw 7.8 earthquake of April 16, 2016, accompanied by coseismic liquefaction phenomena that induced processes of ground subsidence, lateral spreading, sinkhole, and sand boils. The present study proposes the detection and delimitation of the areas affected by the relief deformation, associated liquefaction processes, which occurred in the urban area of Portoviejo city and especially in the Zero Zone of greater destruction after the earthquake, through the application of Differential Interferometry Synthetic Aperture Radar (INSAR) methodology, using Sentinel 1A satellite images, plus the support of geological–geotechnical data obtained from boreholes and standard penetration tests to evaluate the liquefaction potential of the layers of the subsoil based on the Potential Liquefaction Index, considering the seismic scenario of amax 0.5 g for the urban area and the Zero Zone. This procedure allowed the delimitation of areas of high seismic risk for the proper coordination and management of the construction and reconstruction processes in the city of Portoviejo and specifically in the Ground Zero.